.\"
.\" Copyright (c) 2004-2010 The Trustees of Indiana University and Indiana
.\"                         University Research and Technology
.\"                         Corporation.  All rights reserved.
.\" Copyright (c) 2008-2009 Sun Microsystems, Inc.  All rights reserved.
.\"
.\" Man page for ORTE's SnapC Functionality
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.\" .TH name     section center-footer   left-footer  center-header
.TH ORTE_SNAPC 7 "Jun 10, 2020" "4.0.4" "Open MPI"
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.\"    Name Section
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.SH NAME
.
ORTE_SNAPC \- Open RTE MCA Snapshot Coordination (SnapC) Framework: Overview of
Open RTE's SnapC framework, and selected modules.  Open MPI 4.0.4
.
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.\"    Description Section
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.SH DESCRIPTION
.
.PP
Open RTE can coordinate the generation of a global snapshot of a parallel job
from many distributed local snapshots. The components in this framework
determine how to: Initiate the checkpoint of the parallel application, gather
together the many distributed local snapshots, and provide the user with a
global snapshot handle reference that can be used to restart the parallel
application.
.
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.\"    General Process Requirements Section
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.SH GENERAL PROCESS REQUIREMENTS
.PP
In order for a process to use the Open RTE SnapC components it must adhear to a
few programmatic requirements.
.PP
First, the program must call \fIORTE_INIT\fR early in its execution. This
should only be called once, and it is not possible to checkpoint the process
without it first having called this function.
.PP
The program must call \fIORTE_FINALIZE\fR before termination.
.PP
A user may initiate a checkpoint of a parallel application by using the
orte-checkpoint(1) and orte-restart(1) commands.
.
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.\"    Available Components Section
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.SH AVAILABLE COMPONENTS
.PP
Open RTE ships with one SnapC component: \fIfull\fR.
.
.PP
The following MCA parameters apply to all components:
.
.TP 4
snapc_base_verbose
Set the verbosity level for all components. Default is 0, or silent except on error.
.
.\"   full Component
.\" ******************
.SS full SnapC Component
.PP
The \fIfull\fR component gathers together the local snapshots to the disk local
to the Head Node Process (HNP) before completing the checkpoint of the process. This
component does not currently support replicated HNPs, or timer based gathering
of local snapshot data. This is a 3-tiered hierarchy of coordinators.
.
.PP
The \fIfull\fR component has the following MCA parameters:
.
.TP 4
snapc_full_priority
The component's priority to use when selecting the most appropriate component
for a run.
.
.TP 4
snapc_full_verbose
Set the verbosity level for this component. Default is 0, or silent except on
error.
.
.\"   Special 'none' option
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.SS none SnapC Component
.PP
The \fInone\fP component simply selects no SnapC component. All of the SnapC
function calls return immediately with ORTE_SUCCESS.
.
.PP
This component is the last component to be selected by default. This means that if
another component is available, and the \fInone\fP component was not explicity
requested then ORTE will attempt to activate all of the available components
before falling back to this component.
.
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.\"    See Also Section
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.SH SEE ALSO
  orte-checkpoint(1), orte-restart(1), opal-checkpoint(1), opal-restart(1),
orte_filem(7), opal_crs(7)
.
